Abstract
Transitional changes in cell volume under the external osmotic stress was measured by dielectric method to determine the water permeability of the plasma membrane, Lp, which were 0.015, 0.020, and 0.090, 0.033 [pm/(s・Pa)] at 25℃, for rice (Oryza saliva L. ssp. japonica), grape (Vitis sp.), CH27, and yeast (Saccharomyces cerevisiae) cells, respectively. The rate of water removal under osmotic stress was determined both by Lp and the cell diameter, D. The combined parameter, Lp/D was calculated to be 0.73, 0.58, 6.4 and 5.5 [10^<-9> (s・Pa)^<-1>] for rice, grape, CH27, and yeast cells, respectively. The smaller Lp/D for plant cells corresponds to the slower water removal under the freeze-induced osmotic stress, which seemed to explain the difficulty of plant cells in freeze preservation as compared with microorganisms and animal cells.
